The Muslim stronghold in the Philippines in areas such as Jolo and Palawan is located in:
A.Luzon
B.the Visayan archipelago
C.the southern islands
D.Timor
E.metropolitan Manila

Both Jolo and Palawan are islands in (C) the southern part of the Philippines.
Jolo is a volcanic island, which lies at the center of the Sulu Archipelago covering 890 square kilometres (340 sq mi). [ The Sulu Archipelago is an island chain in the Southwest Philippines between Mindanao and Borneo.
Palawan, on the other hand, is composed of the long and narrow Palawan Island, plus a number of

other smaller islands surrounding the main island. The Calamianes Group of Islands to the Northeast consists of Busuanga Island, Coron Island and Culion Island. Durangan Island almost touches the westernmost part of Palawan Island, while Balabac Island is located off the southern tip, separated from Borneo by the Balabac Strait. In addition, Palawan covers the Cuyo Islands in the Sulu Sea. ]